Police in Cambodia are blocking opposition activists from staging a protest march, as both sides spar over intensifying government pressure on its critics.

Police set up a roadblock Monday about 500 meters from the headquarters of the opposition Cambodia National Rescue Party, from which more than 1,000 followers were planning to march to the royal palace to present a petition to King Norodom Sihamoni to support their demand that the government stop arresting and intimidating opposition members.

The government recently applied legal pressure on deputy opposition leader Kem Sokha, accused of carrying on an illicit love affair. The action is widely seen a move to keep the opposition off balance ahead of the 2017 general election. Party leader Sam Rainsy, facing similar pressure, is in exile.